Exposure to Airborne Noroviruses and Other Bioaerosol Components at a Wastewater Treatment Plant in Denmark

Abstract

Exposure to bioaerosols associated with wastewater treatment processes may represent an occupational health risk for workers at wastewater treatment plants (WWTPs). A high frequency of acute symptoms in the gastrointestinal tract among the wastewater workers at a Danish WWTP has been reported. The objective of the study was therefore to examine the exposure of the workers to aerosolised microorganisms. Sampling of inhalable endotoxin, bacteria, moulds and viruses was performed on one occasion using personal samplers. Noroviruses (NoVs) and endotoxin were detected at concentrations that could pose an occupational health risk and possibly contribute to the increased frequency of gastrointestinal illness among the workers and should therefore be investigated further. In addition, positive correlations between exposure to endotoxin, bacteria, moulds and NoVs were found and indicate that the exposure to bioaerosols may be related to work tasks. This is the first study directly showing an occupational exposure to airborne NoVs by its detection in airborne dust.

Aerosolization of Ebola Virus Surrogates in Wastewater Systems

“…33 Another study characterized bioaerosols generated in sewage systems indirectly by measuring endotoxin concentrations; endotoxins are a cell wall component of Gram-negative bacteria. 34,35 Up to 80 ng m -3 of endotoxin were detected in the air samples. To our knowledge, there are no studies on aerosolization of viruses in sewers.…”

“…However, few studies have focused on aerosolization of viruses in wastewater systems. [33][34][35] Aerosolization of bacteria versus viruses could be significantly different due to dissimilarities in their size, structure, and concentration in wastewater. One important difference is that bacteria partition mainly to biosolids while viruses remain suspended in the liquid.…”

Impact of a Sewage Treatment Plant on Health of Local Residents: Gastrointestinal System Symptoms

“…The results of a Dutch research study suggest that when endotoxin concentration in the air ranged from 50-200 EU/m 3 , the risk of diarrhoea among sewage plant employees was approximately 1.5 times higher than in the unexposed group [17]. Also, Danish researchers found that the risk of experiencing gastrointestinal disorders (nausea and diarrhoea) increased with increased concentration of endotoxins in the air [21]. In the present study, we did not measure the concentration of endotoxins in the air, which undoubtedly is a limitation; however, given the increased incidence of reported gastrointestinal disorders in the exposed group as compared to the control group, it can be assumed that the cause of their occurrence was also exposure to endotoxins emitted from the sewage treatment plant.…”

Bioaerosol sampling: sampling mechanisms, bioefficiency and field studies

“…Sampling by filtration is commonplace in aerosol collection but less popular for the collection of bioaerosol particles due to the loss of bioefficiency through desiccation of the pathogen; however, there have been notable successes with filter collection of bioaerosols. 60,61 Fibrous filters consist of layers of fine fibres with relatively substantial gaps between the fibres that allow the filter to be between 70% and 99% air. As particles pass through the filter they are captured by the fibres.…”

“…Personal samplers with various filters include the Inhalable GSP samplers (CIS; BGI, Inc., Waltham, MA, USA) used with Teflon and polycarbonate filters, PAS-6 sampling heads containing polytetrafluoroethylene (PTFE) filters (Millipore, Merck, France) and the Button Aerosol Sampler containing gelatin filters (SKC, Inc.). 23,60,61 Other bioaerosol sampling techniques Less widely used bioaerosol sampling techniques include electrostatic precipitation and condensation techniques. On entering the inlet of an electrostatic precipitator, the bioaerosol particles are electrically charged at the inlet before progressing through an electric field, where they are separated from the air flow and deposited on to charged plates.…”